P53 activation plays a crucial role in silibinin induced ROS generation via PUMA and JNK

Acne Transcriptomics: Fundamentals of Acne Pathogenesis and Isotretinoin Treatment

This review on acne transcriptomics allows for deeper insights into the pathogenesis of acne and isotretinoin's mode of action. Puberty-induced insulin-like growth factor 1 (IGF-1), insulin and androgen signaling activate the kinase AKT and mechanistic target of rapamycin complex 1 (mTORC1). A Western diet (hyperglycemic carbohydrates and milk/dairy products) also co-stimulates AKT/mTORC1 signaling. The AKT-mediated phosphorylation of nuclear FoxO1 and FoxO3 results in their extrusion into the cytoplasm, a critical switch which enhances the transactivation of lipogenic and proinflammatory transcription factors, including androgen receptor (AR), sterol regulatory element-binding transcription factor 1 (SREBF1), peroxisome proliferator-activated receptor γ (PPARγ) and signal transducer and activator of transcription 3 (STAT3), but reduces the FoxO1-dependent expression of GATA binding protein 6 (GATA6), the key transcription factor for infundibular keratinocyte homeostasis. The AKT-mediated phosphorylation of the p53-binding protein MDM2 promotes the degradation of p53. In contrast, isotretinoin enhances the expression of p53, FoxO1 and FoxO3 in the sebaceous glands of acne patients. The overexpression of these proapoptotic transcription factors explains isotretinoin's desirable sebum-suppressive effect via the induction of sebocyte apoptosis and the depletion of BLIMP1(+) sebocyte progenitor cells; it also explains its adverse effects, including teratogenicity (neural crest cell apoptosis), a reduced ovarian reserve (granulosa cell apoptosis), the risk of depression (the apoptosis of hypothalamic neurons), VLDL hyperlipidemia, intracranial hypertension and dry skin.

Saikosaponins: A Review of Structures and Pharmacological Activities

Radix Bupleuri is a traditional medicine widely used in China and other Asian countries. Phytochemistry and pharmacology study reveal that saikosaponins(SSs) are the main bioactive compounds in Radix Bupleuri. SSs are complex compounds composed of triterpene aglycone and carbohydrate part containing 1-13 monosaccharides, which can be divided into seven types based on their structural characteristics. Many different kinds of SSs have been isolated from plants of Bupleurum L. SSs show a variety of biological activities, such as central nervous system protection, liver protection, antivirus, anti-tumor, anti-inflammation, hormone-like effects, and immune regulation functions. Due to their broad activity and favorable safety profile, SSs attract an increasing amount of attention in recent years. In this review, the structures of 86 SSs are summarized based on the different aglycones due to the diverse structures of saikosaponin(SS). The pharmacological effects and related mechanism of SSs are thoroughly reviewed, and perspectives for future research are further discussed.

Crosstalk Between ROS and Autophagy in Tumorigenesis: Understanding the Multifaceted Paradox

Cancer formation is a highly regulated and complex process, largely dependent on its microenvironment. This complexity highlights the need for developing novel target-based therapies depending on cancer phenotype and genotype. Autophagy, a catabolic process, removes damaged and defective cellular materials through lysosomes. It is activated in response to stress conditions such as nutrient deprivation, hypoxia, and oxidative stress. Oxidative stress is induced by excess reactive oxygen species (ROS) that are multifaceted molecules that drive several pathophysiological conditions, including cancer. Moreover, autophagy also plays a dual role, initially inhibiting tumor formation but promoting tumor progression during advanced stages. Mounting evidence has suggested an intricate crosstalk between autophagy and ROS where they can either suppress cancer formation or promote disease etiology. This review highlights the regulatory roles of autophagy and ROS from tumor induction to metastasis. We also discuss the therapeutic strategies that have been devised so far to combat cancer. Based on the review, we finally present some gap areas that could be targeted and may provide a basis for cancer suppression.

Mitochondrial ROS-Mediated Metabolic and Cytotoxic Effects of Isoproterenol on Cardiomyocytes Are p53-Dependent and Reversed by Curcumin

Acute β-adrenergic stimulation contributes to heart failure. Here, we investigated the role of p53 in isoproterenol (ISO)-mediated metabolic and oxidative stress effects on cardiomyocytes and explored the direct protective effects offered by the antioxidant nutraceutical curcumin. Differentiated H9C2 rat cardiomyocytes treated with ISO were assayed for glucose uptake, lactate release, and mitochondrial reactive oxygen species (ROS) generation. Survival was assessed by sulforhodamine B assays. Cardiomyocytes showed significantly decreased glucose uptake and lactate release, as well as increased cellular toxicity by ISO treatment. This was accompanied by marked dose-dependent increases of mitochondria-derived ROS. Scavenging with N-acetyl-L-cysteine (NAC) effectively lowered ROS levels, which completely recovered glycolytic metabolism and survival suppressed by ISO. Mechanistically, ISO reduced extracellular-signal-regulated kinase (ERK) activation, whereas it upregulated p53 expression in an ROS-dependent manner. Silencing of p53 with siRNA blocked the ability of ISO to stimulate mitochondrial ROS and suppress glucose uptake, and partially recovered cell survival. Finally, curcumin completely reversed the metabolic and ROS-stimulating effects of ISO. Furthermore, curcumin improved survival of cardiomyocytes exposed to ISO. Thus, ISO suppresses cardiomyocyte glycolytic metabolism and survival by stimulating mitochondrial ROS in a p53-dependent manner. Furthermore, curcumin can efficiently rescue cardiomyocytes from these adverse effects.

Potential Mechanisms of Plant-Derived Natural Products in the Treatment of Cervical Cancer

Cervical cancer is the second most common gynecological malignancy globally; it seriously endangers women’s health because of its high morbidity and mortality. Conventional treatments are prone to drug resistance, recurrence and metastasis. Therefore, there is an urgent need to develop new drugs with high efficacy and low side effects to prevent and treat cervical cancer. In recent years, plant-derived natural products have been evaluated as potential anticancer drugs that preferentially kill tumor cells without severe adverse effects. A growing number of studies have shown that natural products can achieve practical anti-cervical-cancer effects through multiple mechanisms, including inhibition of tumor-cell proliferation, induction of apoptosis, suppression of angiogenesis and telomerase activity, enhancement of immunity and reversal of multidrug resistance. This paper reviews the therapeutic effects and mechanisms of plant-derived natural products on cervical cancer and provides references for developing anti-cervical-cancer drugs with high efficacy and low side effects.

Plant Polyphenols for Aging Health: Implication from Their Autophagy Modulating Properties in Age-Associated Diseases

Polyphenols are a family of naturally occurring organic compounds, majorly present in fruits, vegetables, and cereals, characterised by multiple phenol units, including flavonoids, tannic acid, and ellagitannin. Some well-known polyphenols include resveratrol, quercetin, curcumin, epigallocatechin gallate, catechin, hesperetin, cyanidin, procyanidin, caffeic acid, and genistein. They can modulate different pathways inside the host, thereby inducing various health benefits. Autophagy is a conserved process that maintains cellular homeostasis by clearing the damaged cellular components and balancing cellular survival and overall health. Polyphenols could maintain autophagic equilibrium, thereby providing various health benefits in mediating neuroprotection and exhibiting anticancer and antidiabetic properties. They could limit brain damage by dismantling misfolded proteins and dysfunctional mitochondria, thereby activating autophagy and eliciting neuroprotection. An anticarcinogenic mechanism is stimulated by modulating canonical and non-canonical signalling pathways. Polyphenols could also decrease insulin resistance and inhibit loss of pancreatic islet β-cell mass and function from inducing antidiabetic activity. Polyphenols are usually included in the diet and may not cause significant side effects that could be effectively used to prevent and treat major diseases and ailments.

A narrative review of multiple mechanisms of progranulin in cancer: a potential target for anti-cancer therapy

Progranulin (PGRN) is an autocrine growth factor and has important effects on regulation of cell growth, motility, tissue repair and embryonic development. Recent years, several researches found the expression of PGRN was at higher levels in a number of cancer cells and its high levels are associated with poor outcome of patients. More and more studies investigated the role of PGRN in cancer and found PGRN exerted various biological functions in cancer cells, such as promoting proliferation, inhibiting apoptosis, inducing migration and invasion of cells, accelerating angiogenesis and enhancing the effectiveness of chemoresistance and radiation. Now the effects of PGRN have been demonstrated in several cancers, including breast cancer, lung cancer, and bladder cancer. In addition, several signaling pathways and molecules are involved in the effects of PGRN on cancer cells, including Akt, mitogen-activated protein kinase (MAPK), vascular endothelial growth factor (VEGF) and cyclin D1. Therefore, PGRN is probably a significant diagnostic and prognostic biomarker for cancer and may be a potential target for anti-cancer therapy. Here, we reviewed the advancing field of PGRN in cancer as well as several signaling pathways activated by PGRN and confirmed PGRN is a key role in cancer. Moreover, future studies are still necessary to elucidate the biological functions and signaling pathways of PGRN in cancer.

TMT-Based Quantitative Proteomic Analysis Identified Proteins and Signaling Pathways Involved in the Response to Xanthatin Treatment in Human HT-29 Colon Cancer Cells

BACKGROUND

Xanthatin is a plant-derived bioactive sesquiterpene lactone from the Xanthium strumarium L., and it has been used as a traditional Chinese medicine. Recently, many studies have reported that xanthatin has anticancer activity. However, a comprehensive understanding of the mechanism underlying the antitumor effects of xanthatin is still lacking.

OBJECTIVE

To systematically and comprehensively identify the underlying mechanisms of xanthatin on cancer cells, quantitative proteomic techniques were performed.

METHODS

Xanthatin induced HT-29 colon cancer cells death was detected by lactate dehydrogenase (LDH) release cell death assay. Differentially abundant proteins in two groups (control groups and xanthatin treatment groups) of human HT-29 colon cancer cells were identified using tandem mass tag (TMT) quantitative proteomic techniques. All the significant differentially abundant proteins were generally characterized by performing hierarchical clustering, Gene Ontology (GO) enrichment analyses and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. We chose Western blot analysis to validate the candidate proteins in the proteomics results.

RESULTS

A total of 5637 proteins were identified, of which 397 significantly differentially abundant proteins in the groups were quantified. Based on the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses, we found that p53-related signaling played an important role in xanthatin-treated HT-29 colon cancer cells. p53-upregulated modulator of apoptosis (Puma), Sestrin-2 and p14ARF, which were selected from among p53-related signaling proteins, were further validated, and the results were consistent with the tandem mass tag quantitative proteomic results.

CONCLUSION

We first investigated the molecular mechanism underlying the effects of xanthatin treatment on HT-29 colon cancer cells using tandem mass tag quantitative proteomic methods and provided a global comprehensive understanding of the antitumor effects of xanthatin. However, it is necessary to further confirm the function of the differentially abundant proteins and the potentially associated signaling pathways.

Targeting the hallmarks of cancer: the effects of silibinin on proliferation, cell death, angiogenesis, and migration in colorectal cancer

Background

Silibinin, as a chemopreventive agent, has shown anti-cancer efficacy against different types of cancers. In the present study, we investigated the anti-cancer activities of silibinin on CT26 mouse colon cell line.

Methods

CT26 cells were treated with different concentrations of silibinin. To examine the cytotoxic effect of silibinin on proliferation, apoptosis, autophagy, angiogenesis, and migration, MTT, colony-forming assay, Annexin V/PI flow cytometry, RT-qPCR, and Scratch assay were used.

Results

Silibinin was found to significantly reduce CT26 cells survival. Furthermore, silibinin strongly induced apoptosis and autophagy by up-regulating the expression of Bax, Caspase-3, Atg5, Atg7 and BECN1 and down-regulating Bcl-2. Silibinin considerably down-regulated the expression of COX-2, HIF-1α, VEGF, Ang-2, and Ang-4 as well as the expression of MMP-2, MMP-9, CCR-2 and CXCR-4.

Conclusions

The present study revealed that silibinin shows anticancer activities by targeting proliferation, cell survival, angiogenesis, and migration of CT26 cells.

Path of Silibinin from diet to medicine: A dietary polyphenolic flavonoid having potential anti-cancer therapeutic significance

In the last few decades, targeting cancer by the use of dietary phytochemicals has gained enormous attention. The plausible reason and believe or mind set behind this fact is attributed to either lesser or no side effects of natural compounds as compared to the modern chemotherapeutics, or due to their conventional use as dietary components by mankind for thousands of years. Silibinin is a naturally derived polyphenol (a flavonolignans), possess following biochemical features; molecular formula C₂₅H₂₂O₁₀, Molar mass: 482.44 g/mol, Boiling point 793 °C, with strikingly high antioxidant and anti-tumorigenic properties. The anti-cancer properties of Silibinin are determined by a variety of cellular pathways which include induction of apoptosis, cell cycle arrest, inhibition of angiogenesis and metastasis. In addition, Silibinin controls modulation of the expression of aberrant miRNAs, inflammatory response, and synergism with existing anti-cancer drugs. Therefore, modulation of a vast array of cellular responses and homeostatic aspects makes Silibinin an attractive chemotherapeutic agent. However, like other polyphenols, the major hurdle to declare Silibinin a translational chemotherapeutic agent, is its lesser bioavailability. After summarizing the chemistry and metabolic aspects of Silibinin, this extensive review focuses on functional aspects governed by Silibinin in chemoprevention with an ultimate goal of summarizing the evidence supporting the chemopreventive potential of Silibinin and clinical trials that are currently ongoing, at a single platform.

Autophagy activated by silibinin contributes to glioma cell death via induction of oxidative stress-mediated BNIP3-dependent nuclear translocation of AIF

Induction of lethal autophagy has become a strategy to eliminate glioma cells, but it remains elusive whether autophagy contributes to cell death via causing mitochondria damage and nuclear translocation of apoptosis inducing factor (AIF). In this study, we find that silibinin induces AIF translocation from mitochondria to nuclei in glioma cells in vitro and in vivo, which is accompanied with autophagy activation. In vitro studies reveal that blocking autophagy with 3MA, bafilomycin A1 or by knocking down ATG5 with SiRNA inhibits silibinin-induced mitochondrial accumulation of superoxide, AIF translocation from mitochondria to nuclei and glioma cell death. Mechanistically, silibinin activates autophagy through depleting ATP by suppressing glycolysis. Then, autophagy improves intracellular H2O2 via promoting p53-mediated depletion of GSH and cysteine and downregulation of xCT. The increased H2O2 promotes silibinin-induced BNIP3 upregulation and translocation to mitochondria. Knockdown of BNIP3 with SiRNA inhibits silibinin-induced mitochondrial depolarization, accumulation of mitochondrial superoxide, and AIF translocation from mitochondria to nuclei, as well as prevents glioma cell death. Furthermore, we find that the improved H2O2 reinforces silibinin-induced glycolysis dysfunction. Collectively, autophagy contributes to silibinin-induced glioma cell death via promotion of oxidative stress-mediated BNIP3-dependent nuclear translocation of AIF.

Natural flavonoid silibinin promotes the migration and myogenic differentiation of murine C2C12 myoblasts via modulation of ROS generation and down-regulation of estrogen receptor α expression

Skeletal muscle regeneration is a complex process, involving the proliferation, migration, and differentiation of myoblasts. Recent studies suggest that some natural flavanones stimulate myogenesis. However, the effect of plant estrogen, silibinin, on the regulation of myoblast behaviors is unclarified. In this study, we investigated the effects of silibinin on immortalized murine myoblast C2C12 in the aspects of proliferation, migration, differentiation along with underlying mechanisms. The results show that silibinin at concentrations below 50 μM enhanced the migration and differentiation of C2C12 cells, but had no effect on cell proliferation. Silibinin significantly promoted the production of ROS, which appeared to play important roles in the migration and differentiation of the myoblasts. Interestingly, among ROS, the superoxide anion and hydroxyl radical were associated with the migration, whereas hydrogen peroxide contributed to the myogenic differentiation. We used ER agonist and antagonist to explore whether estrogen receptors (ERs), which are affected by silibinin treatment in the silibinin-enhanced C2C12 migration and differentiation. Migration was independent of ERs, whereas the differentiation was associated with decreased ERα activity. In summary, silibinin treatment increases ROS levels, leading to the promotion of migration and myogenic differentiation. Negative regulation ERα of differentiation but not of migration may suggest that ERα represses hydrogen peroxide generation. The effect of silibinin on myoblast migration and differentiation suggests that silibinin may have therapeutic benefits for muscle regeneration.

Neferine treatment enhances the TRAIL‑induced apoptosis of human prostate cancer cells via autophagic flux and the JNK pathway

Prostate cancer (PCa) is a common type of cancer among males, with a relatively high mortality rate. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a member of the tumor necrosis factor (TNF) family, initiates the apoptosis of certain cancer cells. Neferine, a primary ingredient of bisbenzylisoquinoline alkaloids, has various antitumor activities. The present study examined the effects of neferine treatment on human PCa cells. Human prostate cancer (DU145) cells were treated with neferine for 18 h, and subsequently treated with TRAIL for 2 h. Combined treatment with neferine and TRAIL significantly decreased cell viability compared to treatment with TRAIL alone. Furthermore, neferine treatment decreased the expression of p62 and increased LC3B-II expression, as assessed by western blot analysis and immunocytochemistry. It was alsp demonstrated that neferine and TRAIL act synergistically to trigger autophagy in PCa cells, as revealed by autophagosome formation, LC3B-II accumulation demonstrated by transmission electron microscopy (TEM) analysis and phosphorylated c-Jun N-terminal kinase (p-JNK) upregulation. When the autophagic flux was attenuated by the inhibitor, chloroquine, or by genetically modified ATG5 siRNA, the enhancement of TRAIL-induced autophagy by neferine-induced was also attenuated. Furthermore, treatment with the JNK inhibitor, SP600125, distinctly increased the viability of the cells treated with neferine and TRAIL. On the whole, the findings of the present study demonstrate that neferine treatment effectively promotes TRAIL-mediated cell death and this effect likely occurs via the autophagic flux and the JNK pathway.

Functional Role of p53 in the Regulation of Chemical-Induced Oxidative Stress

The nuclear transcription factor p53, discovered in 1979, has a broad range of biological functions, primarily the regulation of apoptosis, the cell cycle, and DNA repair. In addition to these canonical functions, a growing body of evidence suggests that p53 plays an important role in regulating intracellular redox homeostasis through transcriptional and nontranscriptional mechanisms. Oxidative stress induction and p53 activation are common responses to chemical exposure and are suggested to play critical roles in chemical-induced toxicity. The activation of p53 can exert either prooxidant or antioxidant activity, depending on the context. In this review, we discuss the functional role of p53 in regulating chemical-induced oxidative stress, summarize the potential signaling pathways involved in p53's regulation of chemically mediated oxidative stress, and propose issues that should be addressed in future studies to improve understanding of the relationship between p53 and chemical-induced oxidative stress.

RNA-seq analysis of testes from flurochloridone-treated rats

Flurochloridone (FLC) is a widely used herbicide in developing countries. Although the testes are a target organ for FLC in rats, the adverse effects of FLC on testes have not been fully elucidated. To clarify them, we performed RNA-seq analysis using the testes of FLC-treated rats from our previous subchronic toxicity tests. Unilateral testes of three male rats from solvent control groupand three FLC-treated groups (3 mg/kg, 31.25 mg/kg and 125 mg/kg) were used for RNA extraction. A poly A selection protocol coupled with an Illumina TruSeq RNA-Seq library protocol was used to construct RNA-Seq libraries. Principal component analysis (PCA), differentially expressed gene (DEG) analysis, and hierarchical clustering analysis (HCA) were conducted using R. Gene Ontology (GO) term enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed to understand the biological characteristics of the DEGs using the Database for Annotation, Visualization and Integrated Discovery (DAVID). The results indicated that many up-regulated DEGs were enriched in pathways associated with testicular injury, such as mitogen-activated protein kinase (MAPK) signaling, lysosome and focal adhesion. Many down-regulated DEGs were enriched in pathways associated with testicular reproduction function, such as sexual reproduction, spermatogenesis and germ cell development. Moreover, we confirmed the oral no-observed-adverse-effect level (NOAEL) of 3 mg/kg in subchronic toxicity test, because the overall testicular gene expression in 3 mg/kg FLC-treated group was similar to that of the solvent control group. In 31.25 mg/kg and 125 mg/kg groups, DEGs revealed that testicular injury was related to oxidative stress.

Differential Effects of Silibinin A on Mitochondrial Function in Neuronal PC12 and HepG2 Liver Cells

The Mediterranean plant Silybum marianum L., commonly known as milk thistle, has been used for centuries to treat liver disorders. The flavonolignan silibinin represents a natural antioxidant and the main bioactive ingredient of silymarin (silybin), a standard extract of its seeds. Mitochondrial dysfunction and the associated generation of reactive oxygen/nitrogen species (ROS/RNS) are involved in the development of chronic liver and age-related neurodegenerative diseases. Silibinin A (SIL A) is one of two diastereomers found in silymarin and was used to evaluate the effects of silymarin on mitochondrial parameters including mitochondrial membrane potential and ATP production with and without sodium nitroprusside- (SNP-) induced nitrosative stress, oxidative phosphorylation, and citrate synthase activity in HepG2 and PC12 cells. Both cell lines were influenced by SIL A, but at different concentrations. SIL A significantly weakened nitrosative stress in both cell lines. Low concentrations not only maintained protective properties but also increased basal mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) levels. However, these effects could not be associated with oxidative phosphorylation. On the other side, high concentrations of SIL A significantly decreased MMP and ATP levels. Although SIL A did not provide a general improvement of the mitochondrial function, our findings show that SIL A protects against SNP-induced nitrosative stress at the level of mitochondria making it potentially beneficial against neurological disorders.

Enhancement of the antimycobacterial activity of macrophages by ajoene

Ajoene, a garlic-derived sulfur-containing compound, has broad-spectrum antimicrobial activity. To assess the potential of ajoene for treating tuberculosis (TB), we determined whether it induces the stress response of the endoplasmic reticulum (ER), which plays an important role in TB. We showed that ajoene stimulation induced the production of ER stress sensor molecules and reactive oxygen species (ROS) levels. Ajoene-induced ROS production was dependent on c-Jun N-terminal kinase (JNK) activation. Interestingly, the inhibition of JNK activity and suppression of ROS production reduced ajoene-induced CHOP production in macrophages. Because ER stress activates autophagy, the activation of which suppresses the growth of mycobacteria, we investigated the ajoene-induced production of autophagy-related factors, including LC3-II, P62 and Beclin-1. As expected, ajoene treatment increased the levels of these factors in RAW 264.7 cells. Remarkably, the total amount of Mycobacterium tuberculosis (Mtb) H37Rv was significantly reduced in ajoene-treated RAW 264.7 cells. The treatment of macrophages with ajoene resulted in the activation of JNK, induction of ROS synthesis and accumulation of ROS, possibly leading to the activation of ER stress and autophagy. These results reveal the mechanism of the antimycobacterial effects of ajoene against Mtb H37Rv. Our findings might facilitate the development of novel therapies for patients with TB.

Combining TRAIL and liquiritin exerts synergistic effects against human gastric cancer cells and xenograft in nude mice through potentiating apoptosis and ROS generation

Gastric cancer is one of the most factors, leading to cancer-related death worldwide. However, the therapies to prevent gastric cancer are still limited and the emergence of drug resistance leads to development of new anti-cancer drugs and combinational chemotherapy regimens. Our study was aimed to explore the anti-gastric cancer effects of liquiritin (LIQ), a major constituent of Glycyrrhiza Radix, which possesses a variety of pharmacological activities. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) preferentially inhibited tumor cells over other normal cells, when used in alone or in combination. The results indicated that LIQ, when applied in single, was moderately effective to suppress proliferation, and migration, as well as to induce apoptosis and reactive oxygen species (ROS) generation of human gastric cancer cell lines, AGS and SNU-216, which are TRAIL-resistant. Significantly, when used in combination, the two drugs functioned synergistically to impede the progression and growth of human gastric cancer cells in vitro and gastric cancer cell xenograft nude mice in vivo. Both intrinsic and extrinsic apoptosis were induced by the two in combination via activating Caspases. And c-Jun N-terminal kinase (JNK) activity was dramatically induced by TRAIL/LIQ. Importantly, TRAIL/LIQ-triggered apoptosis and JNK were dependent on ROS production. The data indicated that application of TRAIL/LIQ in combination had a potential value for clinical use to synergistically prevent human gastric cancer development.

Silibinin Inhibits Proliferation and Migration of Human Hepatic Stellate LX-2 Cells

BACKGROUND

Proliferation of hepatic stellate cells (HSCs) play pivotal role in the progression of hepatic fibrosis consequent to chronic liver injury. Silibinin (SBN), a flavonoid compound, has shown to possess cell cycle arresting potential against many actively proliferating cancers cell lines. The objective of this study was to evaluate the anti-proliferative and cell cycle arresting properties of SBN in rapidly proliferating human hepatic stellate LX-2 cell line.

METHODS

LX-2 cells were fed with culture medium supplemented with different concentrations of SBN (10, 50 and 100 μM). After 24 and 96 h of treatment, total cell number was determined by counting. Cytotoxicity was evaluated by trypan blue dye exclusion test. The expression profile of cMyc and peroxisome proliferator-activated receptor-γ (PPAR-γ) protein expressions was evaluated by Western blotting. Oxidative stress marker genes profile was quantified using qPCR. The migratory response of HSCs was observed by scrape wound healing assay.

RESULTS

SBN treatments significantly inhibit the LX-2 cell proliferation (without affecting its viability) in dose dependent manner. This treatment also retards the migration of LX-2 cells toward injured area. In Western blotting studies SBN treatment up regulated the protein expressions of PPAR-γ and inhibited cMyc.

CONCLUSION

The present study shows that SBN retards the proliferation, activation and migration of LX-2 cells without inducing cytotoxicity and oxidative stress. The profound effects could be due to cell cycle arresting potential of SBN.

Multiple Mechanisms of Anti-Cancer Effects Exerted by Astaxanthin

Astaxanthin (ATX) is a xanthophyll carotenoid which has been approved by the United States Food and Drug Administration (USFDA) as food colorant in animal and fish feed. It is widely found in algae and aquatic animals and has powerful anti-oxidative activity. Previous studies have revealed that ATX, with its anti-oxidative property, is beneficial as a therapeutic agent for various diseases without any side effects or toxicity. In addition, ATX also shows preclinical anti-tumor efficacy both in vivo and in vitro in various cancer models. Several researches have deciphered that ATX exerts its anti-proliferative, anti-apoptosis and anti-invasion influence via different molecules and pathways including signal transducer and activator of transcription 3 (STAT3), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and peroxisome proliferator-activated receptor gamma (PPARγ). Hence, ATX shows great promise as chemotherapeutic agents in cancer. Here, we review the rapidly advancing field of ATX in cancer therapy as well as some molecular targets of ATX.

FTY720 induces autophagy-related apoptosis and necroptosis in human glioblastoma cells

FTY720 is a potent immunosuppressant which has preclinical antitumor efficacy in various cancer models. However, its role in glioblastoma remains unclear. In the present study, we found that FTY720 induced extrinsic apoptosis, necroptosis and autophagy in human glioblastoma cells. Inhibition of autophagy by either RNA interference or chemical inhibitors attenuated FTY720-induced apoptosis and necrosis. Furthermore, autophagy, apoptosis and necrosis induction were dependent on reactive oxygen species-c-Jun N-terminal kinase-protein 53 (ROS-JNK-p53) loop mediated phosphatidylinositide 3-kinases/protein kinase B/mammalian target of rapamycin/p70S6 kinase (PI3K/AKT/mTOR/p70S6K) pathway. In addition, receptor-interacting protein 1 and 3 (RIP1 and RIP3) served as an upstream of ROS-JNK-p53 loop. However, the phosphorylation form of FTY720 induced autophagy but not apoptosis and necroptosis. Finally, the in vitro results were validated in vivo in xenograft mouse of glioblastoma cells. In conclusion, the current study provided novel insights into understanding the mechanisms and functions of FTY720-induced apoptosis, necroptosis and autophagy in human glioblastoma cells.

Aryl Hydrocarbon Receptor Ligand 5F 203 Induces Oxidative Stress That Triggers DNA Damage in Human Breast Cancer Cells

Breast tumors often show profound sensitivity to exogenous oxidative stress. Investigational agent 2-(4-amino-3-methylphenyl)-5-fluorobenzothiazole (5F 203) induces aryl hydrocarbon receptor (AhR)-mediated DNA damage in certain breast cancer cells. Since AhR agonists often elevate intracellular oxidative stress, we hypothesize that 5F 203 increases reactive oxygen species (ROS) to induce DNA damage, which thwarts breast cancer cell growth. We found that 5F 203 induced single-strand break formation. 5F 203 enhanced oxidative DNA damage that was specific to breast cancer cells sensitive to its cytotoxic actions, as it did not increase oxidative DNA damage or ROS formation in nontumorigenic MCF-10A breast epithelial cells. In contrast, AhR agonist and procarcinogen benzo[a]pyrene and its metabolite, 1,6-benzo[a]pyrene quinone, induced oxidative DNA damage and ROS formation, respectively, in MCF-10A cells. In sensitive breast cancer cells, 5F 203 activated ROS-responsive kinases: c-Jun-N-terminal kinase (JNK) and p38 mitogen activated protein kinase (p38). AhR antagonists (alpha-naphthoflavone, CH223191) or antioxidants (N-acetyl-l-cysteine, EUK-134) attenuated 5F 203-mediated JNK and p38 activation, depending on the cell type. Pharmacological inhibition of AhR, JNK, or p38 attenuated 5F 203-mediated increases in intracellular ROS, apoptosis, and single-strand break formation. 5F 203 induced the expression of cytoglobin, an oxidative stress-responsive gene and a putative tumor suppressor, which was diminished with AhR, JNK, or p38 inhibition. Additionally, 5F 203-mediated increases in ROS production and cytoglobin were suppressed in AHR100 cells (AhR ligand-unresponsive MCF-7 breast cancer cells). Our data demonstrate 5F 203 induces ROS-mediated DNA damage at least in part via AhR, JNK, or p38 activation and modulates the expression of oxidative stress-responsive genes such as cytoglobin to confer its anticancer action.

Silymarin as a Natural Antioxidant: An Overview of the Current Evidence and Perspectives

Silymarin (SM), an extract from the Silybum marianum (milk thistle) plant containing various flavonolignans (with silybin being the major one), has received a tremendous amount of attention over the last decade as a herbal remedy for liver treatment. In many cases, the antioxidant properties of SM are considered to be responsible for its protective actions. Possible antioxidant mechanisms of SM are evaluated in this review. (1) Direct scavenging free radicals and chelating free Fe and Cu are mainly effective in the gut. (2) Preventing free radical formation by inhibiting specific ROS-producing enzymes, or improving an integrity of mitochondria in stress conditions, are of great importance. (3) Maintaining an optimal redox balance in the cell by activating a range of antioxidant enzymes and non-enzymatic antioxidants, mainly via Nrf2 activation is probably the main driving force of antioxidant (AO)  action of SM. (4) Decreasing inflammatory responses by inhibiting NF-κB pathways is an emerging mechanism of SM protective effects in liver toxicity and various liver diseases. (5) Activating vitagenes, responsible for synthesis of protective molecules, including heat shock proteins (HSPs), thioredoxin and sirtuins and providing additional protection in stress conditions deserves more attention. (6) Affecting the microenvironment of the gut, including SM-bacteria interactions, awaits future investigations. (7) In animal nutrition and disease prevention strategy, SM alone, or in combination with other hepatho-active compounds (carnitine, betaine, vitamin B₁₂, etc.), might have similar hepatoprotective effects as described in human nutrition.

Silibilin-induces apoptosis in breast cancer cells by modulating p53, p21, Bak and Bcl-XL pathways

Nowadays herbal-derived medicines are attracting attention as new sources of drugs with few side effects. Silibinin is a flavonoid compound with chemotheraputic effects on different cancers such as examples in the prostate, lung, colon and breast. In the present study, the cytotoxic effects of silibinin on MCF7 breast cancer cells were investigated. Apoptosis was determined by flow cytometry and the impact of silibinin on the expression of pivotal genes including Bak, P53, P21, BRCA1, BCL-X1 and ATM was analyzed. Treatment for 24h had a significant dose-dependent inhibitory effect on cell growth (p<0.05) with dose- and time- dependent induction of apoptosis (p<0.05). In addition, there were significant increases in BRCA1, ATM, Bak and Bcl-XL gene expression at the mRNA level with different concentrations of silibinin for 24 or 48 h (p<0.05). Taken together, the results suggest that silibinin inhibits the proliferation and induces apoptosis of MCF-7 cells by down-regulating Bak, P53, P21, BRCA1, BCL-Xl and thus may be considered as an effective adjuvant drug to produce a better chemopreventive response for the cancer therapy.

Expression of PUMA in Follicular Granulosa Cells Regulated by FoxO1 Activation During Oxidative Stress

Many studies have demonstrated that oxidative stress-induced apoptosis is a main cause of follicular atresia. Reactive oxygen species (ROS)-induced granulosa cell (GC) apoptosis is regulated by a variety of signaling pathways involving numerous genes and transcription factors. In this study, we found expression of the p53-upregulated modulator of apoptosis (PUMA), a BH3-only Bcl-2 subfamily protein, in ovarian GCs during oxidative stress. By overexpression and knockdown of Forkhead box O1 (FoxO1), we found that FoxO1 regulates PUMA at the protein level. Moreover, as c-Jun N-terminal kinase (JNK) has been shown to activate FoxO1 by promoting its nuclear import, we used a JNK inhibitor to reduce FoxO1 activation and detected decreased PUMA messenger RNA expression and protein levels during oxidative stress. In addition, in vivo oxidative stress-induced upregulation of PUMA was found following injection of 3 nitropropionic acid in mice. In conclusion, oxidative stress increases PUMA expression regulated by FoxO1 in follicular GCs.

Deconvoluting the role of reactive oxygen species and autophagy in human diseases

Reactive oxygen species (ROS), chemically reactive molecules containing oxygen, can form as a natural byproduct of the normal metabolism of oxygen and also have their crucial roles in cell homeostasis. Of note, the major intracellular sources including mitochondria, endoplasmic reticulum (ER), peroxisomes and the NADPH oxidase (NOX) complex have been identified in cell membranes to produce ROS. Interestingly, autophagy, an evolutionarily conserved lysosomal degradation process in which a cell degrades long-lived proteins and damaged organelles, has recently been well-characterized to be regulated by different types of ROS. Accumulating evidence has demonstrated that ROS-modulated autophagy has numerous links to a number of pathological processes, including cancer, ageing, neurodegenerative diseases, type-II diabetes, cardiovascular diseases, muscular disorders, hepatic encephalopathy and immunity diseases. In this review, we focus on summarizing the molecular mechanisms of ROS-regulated autophagy and their relevance to diverse diseases, which would shed new light on more ROS modulators as potential therapeutic drugs for fighting human diseases.

Silibinin inhibits tumor growth through downregulation of extracellular signal-regulated kinase and Akt in vitro and in vivo in human ovarian cancer cells

Anticancer activity of silibinin, a flavonoid, has been demonstrated in various cancer cell types. However, the underlying mechanisms were not elucidated in human ovarian cancer cells. The present study was undertaken to examine the effect of silibinin in vitro and in vivo on tumor growth in human ovarian cancer cells. Silibinin decreased cell viability in a dose- and time-dependent manner. Silibinin caused an increase in reactive oxygen species (ROS) generation, and the silibinin-induced cell death was prevented by the antioxidant N-acetylcysteine (NAC). Western blot analysis showed silibinin-induced downregulation of extracellular signal-regulated kinase (ERK) and Akt. Transfection of constitutively active forms of MEK and Akt prevented the silibinin-induced cell death. Oral administration of silibinin in animals with subcutaneous A2780 cells reduced tumor volume. Subsequent tumor tissue analysis showed that silibinin treatment induced a decrease in Ki-67-positive cells, an increase in transferase-mediated dUTP nick end labeling (TUNEL)-positive cells, activation of caspase-3, and inhibition of p-ERK and p-Akt. These results indicate that silibinin reduces tumor growth through inhibition of ERK and Akt in human ovarian cancer cells. These data suggest that silibinin may serve as a potential therapeutic agent for human ovarian cancers.

Autophagy induced by silibinin protects human epidermoid carcinoma A431 cells from UVB-induced apoptosis

Ultraviolet B (UVB) in the sun light is a major cause of skin damage, which accompanies complex alterations in irradiated skin cells, including DNA lesions, oxidative stress, inflammation and caspase activation. The protection against UVB damage requires multiple interruptions such as repair of the DNA lesions, scavenging of the reactive oxygen species (ROS), repression of the inflammation and others. Silibinin is suggested as an anti-UVB reagent, but the underlying mechanisms have not been fully elucidated. In this study, we found a role of autophagy in the anti-UVB effect of silibinin in A431 cells. Autophagy was reduced after UVB-irradiation while restored by silibinin through the suppression of the IGF-1R signalling pathway. The protective effect of silibinin in UVB-irradiated A431 cells was further enhanced by pre-treatment with an autophagy inducer, rapamycin, while it was reversed by an autophagy inhibitor, wortmannin, indicating that elevated autophagy contributed to the cell survival. Consistently, cell apoptosis was augmented by siRNAs targeting Beclin 1 and Atg5, supporting the hypothesis that autophagy induced by silibinin plays a protective role against UVB-induced epidermal apoptosis.

Pseudolaric acid B-induced autophagy contributes to senescence via enhancement of ROS generation and mitochondrial dysfunction in murine fibrosarcoma L929 cells

Pseudolaric acid B (PAB) is the primary biologically active compound isolated from the root bark of P. kaempferi Gordon. Our previous study demonstrated that PAB induced mitotic catastrophe in L929 cells and indicated that only a small percentage (12%) of the cells undergoing mitotic catastrophe displayed an apoptotic phenotype after PAB treatment for 72 h. In this study, we found that a minority of the cells undergoing mitotic catastrophe ended in apoptosis, and a majority of them entered a period of senescence. Further data confirmed that PAB induced autophagy, reactive oxygen species (ROS) generation, and mitochondrial dysfunction in L929 cells. Subsequently, we found that autophagy inhibitors significantly delayed the senescence process, indicating that autophagy facilitated senescence. Moreover, ROS scavenger significantly decreased the autophagic level and improved mitochondrial function. Additionally, autophagy inhibitors effectively reduced ROS levels and ameliorated mitochondrial function. In conclusion, autophagy promoted senescence via enhancement of ROS generation and mitochondrial dysfunction in PAB-treated L929 cells.

Gallic Acid Induces a Reactive Oxygen Species-Provoked c-Jun NH2-Terminal Kinase-Dependent Apoptosis in Lung Fibroblasts

Idiopathic pulmonary fibrosis is a chronic lung disorder characterized by fibroblasts proliferation and extracellular matrix accumulation. Induction of fibroblast apoptosis therefore plays a crucial role in the resolution of this disease. Gallic acid (3,4,5-trihydroxybenzoic acid), a common botanic phenolic compound, has been reported to induce apoptosis in tumor cell lines and renal fibroblasts. The present study was undertaken to examine the role of mitogen-activated protein kinases (MAPKs) in lung fibroblasts apoptosis induced by gallic acid. We found that treatment with gallic acid resulted in activation of c-Jun NH₂-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and protein kinase B (PKB, Akt), but not p38MAPK, in mouse lung fibroblasts. Inhibition of JNK using pharmacologic inhibitor (SP600125) and genetic knockdown (JNK specific siRNA) significantly inhibited p53 accumulation, reduced PUMA and Fas expression, and abolished apoptosis induced by gallic acid. Moreover, treatment with antioxidants (vitamin C, N-acetyl cysteine, and catalase) effectively diminished gallic acid-induced hydrogen peroxide production, JNK and p53 activation, and cell death. These observations imply that gallic acid-mediated hydrogen peroxide formation acts as an initiator of JNK signaling pathways, leading to p53 activation and apoptosis in mouse lung fibroblasts.

MicroRNA-21 silencing enhances the cytotoxic effect of the antiangiogenic drug sunitinib in glioblastoma

Highly malignant glioblastoma (GBM) is characterized by high genetic heterogeneity and infiltrative brain invasion patterns, and aberrant miRNA expression has been associated with hallmark malignant properties of GBM. The lack of effective GBM treatment options prompted us to investigate whether miRNAs would constitute promising therapeutic targets toward the generation of a gene therapy approach with clinical significance for this disease. Here, we show that microRNA-21 (miR-21) is upregulated and microRNA-128 (miR-128) is downregulated in mouse and human GBM samples, a finding that is corroborated by analysis of a large set of human GBM data from The Cancer Genome Atlas. Moreover, we demonstrate that oligonucleotide-mediated miR-21 silencing in U87 human GBM cells resulted in increased levels of the tumor suppressors PTEN and PDCD4, caspase 3/7 activation and decreased tumor cell proliferation. Cell exposure to pifithrin, an inhibitor of p53 transcriptional activity, reduced the caspase activity associated with decreased miR-21 expression. Finally, we demonstrate for the first time that miR-21 silencing enhances the antitumoral effect of the tyrosine kinase inhibitor sunitinib, whereas no therapeutic benefit is observed when coupling miR-21 silencing with the first-line drug temozolomide. Overall, our results provide evidence that miR-21 is uniformly overexpressed in GBM and constitutes a highly promising target for multimodal therapeutic approaches toward GBM.

Reactive oxygen species regulation of autophagy in cancer: implications for cancer treatment

Reactive oxygen species (ROS) are important in regulating normal cellular processes, but deregulated ROS contribute to the development of various human diseases including cancers. Autophagy is one of the first lines of defense against oxidative stress damage. The autophagy pathway can be induced and upregulated in response to intracellular ROS or extracellular oxidative stress. This leads to selective lysosomal self-digestion of intracellular components to maintain cellular homeostasis. Hence, autophagy is the survival pathway, conferring stress adaptation and promoting viability under oxidative stress. However, increasing evidence has demonstrated that autophagy can also lead to cell death under oxidative stress conditions. In addition, altered autophagic signaling pathways that lead to decreased autophagy are frequently found in many human cancers. This review discusses the advances in understanding of the mechanisms of ROS-induced autophagy and how this process relates to tumorigenesis and cancer therapy.

Pifithrin-μ increases mitochondrial COX biogenesis and MnSOD activity in skeletal muscle of middle-aged mice

We investigated the biogenesis and mitochondrial antioxidant capacity of cytochrome c oxidase (COX) within the skeletal muscle under the treatments of p53 inhibitors (pifithrin, PFTα and PFTμ). Significantly, PFTμ increased mtDNA content and COX biogenesis. These changes coincided with increases in the activity and expression of manganese superoxide dismutase (MnSOD), the key antioxidant enzyme in mitochondria. Conversely, PFTα caused muscle loss, increased oxidative damage and decreased MnSOD activity in intermyofibrillar (IMF) mitochondria. Mechanically, PFTμ inhibited p53 translocation to mitochondria and thus increased its transcriptional activity for expression of synthesis of cytochrome c oxidase 2 (SCO2), an important assembly protein for COX. This study provides in vivo evidence that PFTμ, superior to PFTα, preserves muscle mass and increases mitochondrial antioxidant activity.

Regulation of PUMA induced by mechanical stress in rat cardiomyocytes

Background

PUMA (p53-up-regulated modulator of apoptosis), an apoptosis regulated gene, increased during endoplasmic reticulum stress. However, the expression of PUMA in cardiomyocytes under mechanical stress is little known. We aimed to investigate the regulation mechanism of PUMA expression and apoptosis induced by mechanical stress in cardiomyocytes.

Methods

Aorta-caval (AV) shunt was performed in adult Wistar rats to induce volume overload. Rat neonatal cardiomyocytes were stretched by vacuum to 20% of maximum elongation at 60 cycles/min.

Results

PUMA protein and mRNA were up-regulated in the shunt group as compared with sham group. The increased PUMA protein expression and apoptosis induced by shunt was reversed by treatment with atorvastatin at 30 mg/kg/ day orally for 7 days. TUNEL assay showed that treatment with atorvastatin inhibited the apoptosis induced by volume overload. Cyclic stretch significantly enhanced PUMA protein and gene expression. Addition of c-jun N-terminal kinase (JNK) inhibitor SP600125, JNK small interfering RNA (siRNA) and interferon-γ (INF-γ) antibody 30 min before stretch reduced the induction of PUMA protein. Gel shift assay demonstrated that stretch increased the DNA binding activity of interferon regulatory factor-1. Stretch increased, while PUMA-Mut plasmid, SP600125 and INF-γ antibody abolished the PUMA promoter activity induced by stretch. PUMA mediated apoptosis induced by stretch was reversed by PUMA siRNA and atorvastatin.

Conclusions

Mechanical stress enhanced apoptosis and PUMA expression in cardiomyocytes. Treatment with atorvastatin reversed both PUMA expression and apoptosis induced by mechanical stress in cardiomyocytes.

6-Gingerol Inhibits Growth of Colon Cancer Cell LoVo via Induction of G2/M Arrest

6-Gingerol, a natural component of ginger, has been widely reported to possess antiinflammatory and antitumorigenic activities. Despite its potential efficacy against cancer, the anti-tumor mechanisms of 6-gingerol are complicated and remain sketchy. In the present study, we aimed to investigate the anti-tumor effects of 6-gingerol on colon cancer cells. Our results revealed that 6-gingerol treatment significantly reduced the cell viability of human colon cancer cell, LoVo, in a dose-dependent manner. Further flow cytometric analysis showed that 6-gingerol induced significant G2/M phase arrest and had slight influence on sub-G1 phase in LoVo cells. Therefore, levels of cyclins, cyclin-dependent kinases (CDKs), and their regulatory proteins involved in S-G2/M transition were investigated. Our findings revealed that levels of cyclin A, cyclin B1, and CDK1 were diminished; in contrast, levels of the negative cell cycle regulators p27^Kip1 and p21^Cip1 were increased in response to 6-gingerol treatment. In addition, 6-gingerol treatment elevated intracellular reactive oxygen species (ROS) and phosphorylation level of p53. These findings indicate that exposure of 6-gingerol may induce intracellular ROS and upregulate p53, p27^Kip1, and p21^Cip1 levels leading to consequent decrease of CDK1, cyclin A, and cyclin B1 as result of cell cycle arrest in LoVo cells. It would be suggested that 6-gingerol should be beneficial to treatment of colon cancer.